Many pressure transducer assemblies include a header portion that houses a sensing element and a port portion. An attachment between the header and port portions can enable electrical connection between the sensing element and the remaining electronic components within the pressure transducer assembly. The attachment between the header and the port also serves to seal and contain the pressure media in the measurement environment (such as in a manifold, pipe, etc.) while isolating the electrical components from the media and further allowing assembly of the electronics within the pressure-sensing sub assembly.
Typically, the header portion is welded to the port portion. In certain prior art embodiments, the header portion includes a threaded section that mates with a corresponding threaded section on the port portion, as illustrated in FIG. 1. In this prior art embodiment, the threaded portions 125 are configured to take the load off the welded portion 130. In use, the welded portion 130 may experience stresses due to internal pressures in the design. These stresses include the hoop stress or tangential stress, and radial stress.
It was once believed that the thread would aid in removing the tensile stress from the weld area. However, several micrographs of experimental and production designs indicate that the threads may become disengaged during welding, thereby placing tensile stress on the welded area. The weld is typically an electron beam weld, and as the material melts to form the weld, a preload on the structure may be removed. Consequently, the removal of the preload during the welding process may increase the stress on the welded portion and can considerably reduce the fatigue life of the pressure transducer assembly. A need exists for an improved tensioning systems and methods.